The Winter Tire Symbol vs the M+S Marking

This is the single most useful thing to know when reading a tire sidewall, and it catches a surprising number of people who believed they had winter tires.

The three peak mountain snowflake

A pictogram of three mountain peaks with a snowflake inside.

A tire wearing this symbol has passed a standardised snow traction test. It had to achieve a defined level of acceleration performance on packed snow against a reference tire. It is a measured result, not a marketing claim.

This is the only sidewall marking that tells you anything verified about winter performance.

M+S

Stands for mud and snow.

It means the tread pattern meets certain geometric requirements: a given proportion of void area, block edges of a certain kind. It describes the shape of the tread.

There is no performance test. No snow traction requirement. No cold weather compound requirement. A manufacturer applies it based on the tread design meeting the geometry.

Almost every all season tire sold carries it.

Why the difference is not academic

What makes a winter tire work is not mostly the tread pattern. It is the compound.

All season rubber is formulated to last in summer heat. Below about seven degrees Celsius it stiffens. A stiff tire cannot conform to the texture of the road surface, and grip comes from conformity. On a cold morning at minus five on bare dry pavement, an all season has already lost a meaningful amount of braking grip, before any snow is involved.

Winter compound stays pliable in the cold. That is the whole point, and it is invisible from the outside.

M+S tells you about the pattern. The snowflake tells you about the tire.

What this means in practice

Your tires say M+S only: they are all season tires. They are legal, they are fine in three seasons, and they are not winter tires. In snow and on cold pavement they perform like what they are.

Your tires have the snowflake: they met a snow traction standard. They are either winter tires or all weather tires.

Your tires have both: normal. Most winter tires carry M+S as well, because the tread geometry qualifies. The snowflake is the meaningful one.

All season, all weather, winter

The terms get used loosely, so here is the clean version:

All season: M+S, no snowflake. Three season tire. Despite the name, not intended for real winter conditions.

All weather: carries the snowflake. Built to be run year round. A genuine compromise, better than all season in winter, not as good as a dedicated winter tire in snow and ice, and wears faster than an all season in summer.

Winter: carries the snowflake. Soft compound, deep siping, intended to be removed in spring. The best winter grip available, and worst in summer heat.

The gap between all season and all weather is the snowflake. It is a real distinction and the names do a poor job of signalling it.

Where to look

Stand at the side of the tire and read around the sidewall. You will find the size, the load index and speed rating, the DOT code with the manufacture date, and the markings. The snowflake is usually near the size.

If you are checking a set that has been in the basement since April, check all four. Mixed sets happen, especially on used cars, and finding out in a snowstorm is a bad time.

If it turns out you do not have winter tires

Come in and we will size a set for your vehicle and tell you straight whether studded, studless or all weather makes sense for the driving you actually do. Over 25,000 tires we can get, same day on everything in store.